Cannot access to (or find out) main Settings program

I am using Ubuntu 18.04 LTS.

After removed Ibus Preferences & Input Method I'm not able to find out the main Settings program. There are somethings I have tried:

Hit Windows button on keyboard then find Settings (Settings not show on search result).
Click Power button on top right screen, then click on Setting button.
Try to right click on desktop screen then choose Change Background.

But nothing helps.

How can I fix it?

Solution 1:

Reinstall Settings (aka gnome-control-center) by running

sudo apt-get install --reinstall gnome-control-center

in Terminal.